Once you arrive to the final cutscene DO NOT! skip. Leave your controller still or keep your finger off the B button if you can resist the skip temptation. And wait about 8 minutes (I suggest going to Walmart and buying a glass bottle Yoo-hoo that you can drink once you get to this final cutscene) once your achievement pops right before a bunny is even shown on screen you can skip. I might as well add that the “Full throttle unlock every achievement” will not unlock until you start a new game. After starting a new game the achievement should pop almost instantly as the beginning of the first cutscene starts playing. Thankyou member ShodanPT for alerting me that the achievement may not unlock if you move or press anything on your controller while playing. If you can make sure you save the game before the ending so you can resume from a non auto save. Auto saves seem to negate this achievement at least from what shodanpt claims. I’ll paste an important part of his comment here.
(5th try - loaded the last save (not the autosave) and played the final part and left the game running (disabled the idle screensaver option on the xbox), came back 15m and the achievement popped.)